Side effects of abamectin and hexythiazox on seven predatory mites

Abstract

Abstract Use of acaricides has become a common practice to control pests all over the world including Saudi Arabia. In spite of killing the targeted pests, such insecticides also effect growth of predatory mites. Present study has been conducted to evaluate the impact of two acaricides, abamectin and hexythiazox, on seven species of predatory mites. Standard solutions of abamectin (8.4% w/v) and hexythiazox (10% w/w) were purchased and prepared for direct spray. Acaricides were tested at three serial concentrations of recommended dose (RD), half of the recommended dose (HRD) and double the recommended dose (DRD). Trials were made on eggs, nymphs and adults of the seven species of predatory mites under laboratory conditions. Effect of the applied acaricides was determined one week after the application. The results of the study revealed that all doses of hexythiazox and abamectin are toxic to the nymphs and adults of all seven species of predatory mites but to the variable extent. Furthermore, it was observed that hexythiazox and abamectin reduced the percentage of egg hatching for all seven species of predatory mites. Hexythiazox was found to be more toxic than abamectin to all seven predatory mites. Higher mortality was recorded at DRD and RD, while minimum mortality was recorded at HRD. Acaricidal effect is less severe on hatching eggs than on immatures and adults of the predatory mites. Species vary in susceptibility to acaricides and in some populations resistance has been observed. Based upon this study, it is recommended that the frequent use of acaricides against phytophagous mites should be avoided and feasibility of biological control programs should be promoted to protect the environment, health of living individuals and the non-target organisms.